Seung-Yo Lee

Comparison of Different Designs of a 42-V/14-V DC/DC Converter Regarding Losses and Thermal Aspects

In this paper, thermal analysis for a 42-V/14-V bidirectional dc/dc converter with integrated inductors is performed. An interleaved dc/dc converter system with four channels was chosen for the automotive-converter topology with 42-V/14-V dual-output voltages. Coupled inductors were designed and used for the four-channel dc/dc converter. A 3-D thermal model based on finite-element modeling using I-DEAS is presented and the thermal behavior of the dc/dc converter system is simulated and analyzed. The thermal model includes a printed circuit board, integrated inductors, a heat sink, and switching devices (MOSFETs). The analyzed thermal result can help to design a converter system under severe ambient-temperature conditions

A new control strategy for instantaneous voltage compensator using 3-phase PWM inverter

In a three-phase power system, unbalanced voltage with harmonics can be detected on the synchronous reference frame. Assuming that there is no neutral path in the power system, an unbalanced voltage with harmonic components has a DC component, a 2nd harmonic and the other harmonic components. Therefore, it is possible to compensate unbalanced voltage and harmonic voltage by cancelling the harmonic components, exclusive of the DC component on the d-q axis. In addition, by adjusting the value of the DC component obtained from positive sequences, the regulation of load voltage is achieved. This paper presents an algorithm performing compensation of unbalanced and harmonic voltage as well as maintaining the constant voltage in the load side. The compensating characteristics of the proposed instantaneous voltage compensator are also discussed.

A 3-phase series active power filter with compensate voltage drop and voltage unbalance

In this paper, a three-phase series active power filter to compensate harmonic current, voltage drop and unbalanced voltage in power distribution systems is studied. The main circuit of the APF consists of a voltage source inverter with space vector modulation and a high pass filter connected in parallel to the power system. The APF is connected in series to the transmission line through a single-phase transformer with a turns ratio of 1:1. Here, the load is a six-pulse thyristor rectifier. The phase angle detected in order to generate the reference voltage at the load terminal is synchronized with the positive sequence component of the unbalanced source by using symmetrical component transformation. The proposed system has harmonic isolation between the source and load, voltage regulation and unbalance compensation. To verify the validity of the proposed compensating system, both computer simulations and experiments are carried out.

Thermal stress and intrinsic residual stress in embedded power modules

In embedded power modules, mechanical properties of interfaces between deposited copper traces and substrates are important for reliable operation. This paper investigates the values of thermal-mechanical stresses by IDEAS simulation, and describes an experimental method to calculate intrinsic residual stresses using Stoney equation based on the sample bending curvature.

Analysis and design of modified deadbeat controller for 3-phase uninterruptible power supply

This paper proposes a modified deadbeat control scheme of 3-phase PWM inverter with LC filter for uninterruptible power supply (UPS). The deadbeat current and voltage controller are used to obtain the fast transient response of the UPS system in general. However, the conventional deadbeat controller has a defect and becomes unstable. In this paper, to remove the defect which makes a system unstable due to the same pole placement of a conventional deadbeat current and voltage controller, modified deadbeat algorithm, which produces a first-order exponential response during one input step, is proposed. Because the overall controller is constructed by deadbeat control, the response of the proposed control system is fast and the structure of the controller is simple. In addition, the full-order state and disturbance observer is constructed to compensate the disturbances generated by a sudden change of load currents. The proposed disturbance observer estimates state values of load currents within a finite time, and cancels the disturbances by adding a feedforward compensation loop in the control system. The validity of the modified deadbeat control scheme is proved by the results of simulation and experiment.

Thermal analysis for series LC integrated passive resonant module based on finite-element modeling

In recent years, the passive integrated power electronic module (IPEM), which has been implemented as resonant tank in resonant DC-DC converters, has gained research interest because of its merits for possibly reducing the total volume of the resonant converter system. In this paper, thermal analysis for a series resonant LC passive IPEM is performed. Especially, a 3-dimensional thermal model based on finite-element modeling (FEM) using I-DEAS is presented and the thermal distribution of the integrated passive module is simulated. In order to verify the thermal analysis results, an experimental prototype LC passive REM was constructed and temperature distribution measured using an IR (Infrared) camera and thermocouples and compared to simulation results. A good correlation between the 3-D thermal model and thermal test results was achieved. Moreover, 1-dimensional thermal analysis was also performed and presented to compare results of the hot spot temperatures in the interior of the passive IPEM using the 1-D and the 3-D models.

Thermal analysis for a coupled inductor for 4-channel interleaved automotive bi-directional DC/DC converter based on finite-element modeling

In this paper, thermal analyses for inductors with integrated structure designed for an automotive bi-directional DC/DC converter are performed. An interleaved DC/DC converter system with 4-channels was chosen for the automotive converter topology with 42 V/14 V dual output voltages. The coupled inductors were designed and used for the 4-channel DC/DC converter. A 3-dimensional thermal model based on finite-element modeling (FEM) using I-DEAS is presented, and the thermal behavior of the integrated inductors is simulated and analyzed. The analyzed thermal result can help to design inductors considering severe ambient temperature conditions.

Thermo-mechanical stress analysis for an integrated passive resonant module

In this paper, thermo-mechanical stress analysis for a series resonant passive integrated power electronic module (IPEM) is presented. The passive IPEM has in the past been implemented as a resonant tank in resonant DC-DC converters. It has some merits for reducing the total volume of the resonant converter system and improving manufacturability, but this integration process increases the complexity of the thermal and mechanical behavior of the structure due to interactive heating of the module layers and mechanical inter-layer stresses. It is therefore essential to investigate the thermo-mechanical behavior of an IPEM to ensure reliable operation. This paper presents a 3-dimensional thermo-mechanical model based on finite-element modeling (FEM) using I-DEAS software. Results of the thermal analysis and the associated thermal stress analysis are also discussed.

A novel detecting noise reduction scheme for voltage-regulated current-fed power filter

Active power filters have been developed to solve the harmonics disturbance problems on power system networks. Particularly for current-type active power filters, a voltage regulation scheme is considered to control the voltage of capacitor at the input side of a nonlinear load. For precise control, the value of voltage drop at the AC side must be included. Because of the reactance of the filter, external noises are added to the detected voltage drop signal and hence the resultant signals will be seriously distorted, particularly where an electronic differentiator is used. To reduce these noises, a novel detected noise reduction scheme with an observer based algorithm is proposed. The designed observer algorithm is applied and then investigated by digital simulation. Also the experimental results are shown to verify the validity of proposed scheme.

A novel active series voltage compensator with harmonic current compensating capability

A novel unbalance voltage compensator with harmonic current compensating capability is proposed. The proposed system performs both compensations of the unbalanced source voltage and the harmonic currents generated due to nonlinear loads such as diode rectifiers. The operating principle of the proposed system is described through a single-phase equivalent circuit and the control strategy is suggested on the d-q rotating reference frame of the 3-phase system. In addition, a new method for phase angle detection synchronized by positive sequence component under unbalanced source voltage is proposed and this detected phase angle is used for d-q transformation. The proposed system is composed of a 3-phase voltage source converter, LC filter, series transformer and passive device at the load side of the line. The compensating voltage to regulate the load voltage and to remove the harmonic current components at the source side is transmitted to the line by the series transformer.